The present invention relates to a method for development of silver halide photographic light-sensitive materials and particularly to a developer used therefor.
In general, it is known that developer used for development of silver halide photographic light-sensitive materials contains a sulfate for increasing storage stability of the developer. In some case, there are used developers which contain a compound such as a thiosulfate having strong dissolving action on silver halide such as developers for silver complex diffusion transfer process and combined developing and fixing baths.
When light-sensitive materials are treated with developer containing compound having dissolving action on silver halide such as sulfate or thiosulfate, a large amount of silver complex dissolves into the developer and this silver complex is readily reduced and accumulated as silver sludge. Especially when light-sensitive material is continuously treated by automatic processor, not only the silver sludge floats, but also it sticks to roller or belt to result in stains on the light-sensitive material due to the precipitated silver which are called silver stains in the form of streaks of rollers and which appear yellow or brown upon reflection of light.
As inhibitors for formation of silver sludge and contamination of developer, there are known 2-mercapto-1,3,4-thiadiazoles (British Patent No. 940169), 2-mercapto-1,3,4-oxadiazoles or 1-phenyl-5-mercaptoterazoles (U.S Pat. No. 3,173,789), D.L.-6,8-dithiooctanoic acid (U.S. Pat. No. 3,318,701), o-mercaptobenzoic acid (British Patent No. 1144481), aliphatic mercaptocarboxylic acids (U.S. Pat. No. 3,628,955), L-thiazolidine-4-carboxylic acids [J. Photogr. Sci., 13, 233 (1965)], disulfide compounds [Japanese Patent Kokai (Laid-Open) No. 52-36029], 2-benzoxazole thiol, 2-benzimidazole thiol [Photgr. Sci. Eng., 20, 220 (1976)], acetylene glycols [Japanese Patent Kokai (Laid-Open) No. 55-95947], and 2-mercaptobenzothiazole-5-sulfonic acid [Japanese Patent Kokai (Laid-Open) No. 56-72441].
However, when these compounds are used in developers having dissolving action on silver halide, especially developers containing a sulfate in high concentration (e.g., 0.2 mol/1 or more) as sludge inhibitor, there are the problems that they lose sludge inhibiting effect or are weak in sludge inhibiting effect and must be used in a large amount, they have adverse effect on photographic characteristics such as reduction in sensitivity, low contrast and retardation in development, and besides they are expensive or have an offensive odor.